<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
		<!--[if lt IE 9]>
    <script src="jquery-1.9.0.js"></script>
<![endif]-->
		<!--[if gte IE 9]><!-->
		<script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
		<!--<![endif]-->
		<script type="text/javascript">
			i = 0;
			$(document).ready(function() {
				$("input").keypress(function() {
					$("span").text(i += 1);
				});
			});
		</script>
	</head>

	<body>

		输入你的名字: <input type="text">
		<p>按键的次数: <span>0</span></p>
	</body>

</html>